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RF sync of multipler AD9371 devices, boards

Question asked by RajatRao on Jun 2, 2018
Latest reply on Jun 11, 2018 by Vinod

Hello,

 

I am designing a system consisting of multiple AD9371 ICs per board, and multiple such boards exist in the entire system. I have 4 questions about synchronizing the devices on the same board and across boards - 

  1. Digital syncing is achieved by the JESD SYSREF signal. So, as long as the same SYSREF is fed to each of the boards and then to each AD9371 on the boards, digital MCS should not be a problem. Is this correct?
  2. For RF sync, I looked at the following link: https://wiki.analog.com/resources/eval/user-guides/ad-fmcomms5-ebz/multi-chip-sync?s[]=mcs#multi-chip_sync_mcs. It shows how RF MCS is achieved on the FMCOMMS5 board. I would like to implement something similar using ADG918 switches. However, there are some differences between AD9361 and AD9371.  AD9361 has two muxed Tx TX1A, TX1B. The eval board has one connected to the switch for MCS and the other can be used as output to the antenna. With AD9371, the same TX1 pair needs to be connected to both places which means one path needs to be disabled when the other is working. Does ADI have any reference design for doing this? If not, please tell me how to do it?
  3. Assuming the connection with the switch is resolved, how do I sync multiple devices on the same board? Can I do it as a chain sync, i.e. sync device 1 with 2, then device 2 with 3, and so on? This will require 1 pair of ADG918 switches for every 2 AD9371 ICs.
  4. Finally, how do I sync across boards? Does it make sense to route the switch output from one board to another one? Can I use the same chained approach?

 

Thanks,

Rajat Rao

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